The Ishikawa diagram is a graphical method for finding the most likely causes for an undesired effect. The method was first used by Kaoru Ishikawa in the 1960s. Because of its shape, it is also known as the fishbone diagram. Another name for this technique is: the cause-and-effect diagram. The fishbone diagram is a method used in a large verity of business situations and is also known as root cause analysis.
The most common use of the Ishikawa diagram is in product design, to identify factors leading to the final effect. Mazda Motors used a Ishikawa diagram in the development of the Miata sports car, where the required result was "Jinba Ittai" or "Horse and Rider as One". The main causes included such aspects as "touch" and "braking" with the lesser causes including highly granular factors such as "50/50 weight distribution" and "able to rest elbow on top of driver's door". Every factor identified in the diagram was included in the final design.